A special method used in tyre construction links living, in part alkali-metal-terminated, polymers based on conjugated dienes or based on conjugated dienes and on vinylaromatic compounds to organic or inorganic compounds particularly suitable for this purpose, thus improving processing properties in particular, and also physical and dynamic properties, in particular those connected with rolling resistance in tyres.
The linking/coupling agents used for the rubbers mentioned in the industry comprise not only a very wide variety of organic compounds having appropriate groups capable of linkage to the living polymers, e.g. epoxy groups (German Auslegeschrift 19 857 768), isocyanate groups, aldehyde groups, keto groups, ester groups, and halide groups, but especially also appropriate compounds of silicon or of tin (EP-A 0 890 580 and EP-A 0 930 318), for example their halides, sulphides or amines. German Auslegeschrift 19 803 039 describes rubber compositions for high-performance tyre treads, the underlying rubbers of which have to some extent been coupled with tin compounds, phosphorus compounds, gallium compounds or silicon compounds.
There are also various known methods for end-group functionalization of polydienes. In the case of polybutadiene catalyzed via neodymium-containing systems, examples of compounds used are epoxides, substituted keto compounds from the group of ketones, aldehydes or acid derivatives, or substituted isocyanates, as described by way of example in U.S. Pat. No. 4,906,706. Another known method of end-group modification uses doubly functionalized reagents. These react with the polydiene, using the polar functional group, and use a second polar functional group in the molecule to interact with the filler, as described by way of example in WO 01/34658 or U.S. Pat. No. 6,992,147.
Some of the linking agents used hitherto have considerable disadvantages, for example leading to end-group modification in diene polymerization reactions catalyzed via rare earths, in particular via neodymium-containing systems, thus being unsuitable as coupling agents.